The next stage was to fit the prop tubes and motors, MMModels prop tubes and T4 motors were used. Now I will admit that getting the tubes lined up and getting them to come out of the hull nearly horizontal gave me a lot of headaches. The hull had different thicknesses and shapes of fibreglass were the motors had to be fitted, the A frame markings on the hull, especially the inboard ones were way out, all of this plus the fact that the motors had to be fitted more or less on the bottom of the hull. Aligning pieces were made on the lathe to go between the prop shafts and the motors. Motor mounts were made from hardwood and shaped on a belt sander to fit the hull bottom. I think I had about five attempts at this stage using all sorts of pieces of ply with holes in them, wooden wedges and of course masking tape. Motor mounts, I only have one photo of these, holes drilled in hardwood with a hole cutter, then cut in two on the bandsaw to give two halves that can clamp the motor, draught excluder stuck on the inside and the two halves fastened together with two wood screws.

Useful info on how to fit a bearing. Do yo intend to provide any protection from water ingress or are you relying on the oiler alone? It would be useful to know the specs (max revs) for the bearing, especially if you intend to fit a brushless motor.

Well now that my prop stuff arrived. I fent like working on the seam. That goes far and aft in the hull! Had to place a 1" wide fiberglass ribbon. Along the middle of the hull! Reinforcing the hulls inner keel!👍

Many thanks Dave and Brian, I guess Brian's craft is much bigger and heavier than mine; 56x30 cm. Spec says weight 1.3kg with motors fitted but without batteries and RC gear. It came with a 9cm diameter 3 blade ducted fan, 13x? two blade thrust prop and a pair of 400 size brushed motors, the mountings for which limit me to 28/30mm diameter brushless. When I hauled the kit box down from an upper shelf to investigate I found the packing list and spares price list in both Deutschmark and Euro, i.e. circa 1999/2000!! Planning well ahead for the retirement 😉😉 In mine there are no rudders! The whole motor/prop mount is turned. Will see how it goes with that and maybe mod it later with rudders depending on how easy it is to control - OR NOT😲 many thanks for the tips 👍 Doug

Excellent 👍 I now have a new task for my recently acquired mini lathe. Already have several mini bearings waiting for something to do. Have already used the lathe to make new shafts, only logical to continue with the tubes and bearing housings. Ta for the shove 😉

Propshaft and oiler fitting Now for the fitting of the propshaft, fortunately I have a long series drill that will go through the keel and through the bulkhead B4 into the motor compartment; this went well and came out in the expected place. Next a trial fit of the tube in the keel and into the skeg, again this lined up perfectly and all that needed to be done was to epoxy it into place. First I nearly forgot to fit the oiler system to the prop tube, careful drilling and deburring and making sure no swarf is left in the tube. Finally wrapping a piece of plumber’s PTFE gas tape around the tube to ensure a gas tight fit (oil tight) we are ready to commit the tube to final fixing. Epoxy mixed and applied I put a couple of small wedges in the skeg to stop it moving and a wedge under the oiler to make sure it was horizontal.

Prop shaft bearing I purchased a standard propshaft with Phosphor bronze bearings again from a well-known supplier, however I had also fancied a Raboesch type with a bearing at the motor end however at £30 plus think again. So I researched the bearing type and found at £2.50 each it was worth a go at making my own so quick sketch and an order placed from Modelfixings.com. A simple piece of machining and the part was made. A simple enough job to remove the existing bearing and slide on the new housing and it made a significant difference to the “feel” of the shaft when rotated. I also made a simple collar to retain the shaft in the hosing.

As requested I have obtained some pics from Brian Clewes's Hovercraft. The motors are 900 Kv with 80 amp Escs the lift fan is a 7 blade ducted fan, the thrust prop is a 12in x7in cut down to 10in. Battery is 14.8v 5000Ma.

At this point I decided to fit the rudder tube, water pick up and skeg. I was able to mount the boat in the machine vice by gripping the keel; this ensured that the holes are drilled absolutely true and square, 2 x 8mm holes are needed to take both the rudder tube and water scoop. I purchased the rudder assembly from a well-known supplier but I didn’t like any of the proprietary water scoop tubes on offer so decided to make my own. Whilst the boat is in the vice I also decided to machine the slot for the skeg to fit in. This required drilling a series of 2mm holes and then opening them up into a slot using a long series slot drill again giving an accurate slot which the skeg can locate into. Water scoop Having dealt with the woodwork, I turned my attention to metalwork. To bend the ¼” brass tube successfully it has to be annealed, (cherry red and quenched in water), then inserting a tight fitting spring inside the tube to stop any kinking I gently pressed it round a former to the correct shape. Springs removed I filed the end to the correct angle which gives an oval opening, but the end didn’t look finished, so I machined a thin spacer and then squashed it to suit the oval end and silver soldered it to the end of the tube, this gives a much better visual appearance.

Hi Graham You do have to support the prop shaft close to the bearings at each end. This is vital if you are to avoid a slight imbalance developing into an uncontrolled whipping and as you have experienced, damage to the shaft assembly. The support needs to be firmly attached to the hull and shaft close to the bearing to provide both vertical and horizontal support. The supports should ideally be within 1/8" of the bearings. If you are reinstalling the prop shaft then, as others have suggested, it may be an opportunity to move the motor towards the stern and use a shorter shaft, but still providing support near the bearings.